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A Problem with Simplify


I have the following rather simple integral of two sines, which should 
evaluate to zero if m is not equal to n and to L/2 if they are the same.

The following is just fine

Imn = Simplify[Integrate[
        Sin[(m*Pi*x)/L]*
          Sin[(n*Pi*x)/L],
        {x, 0, L}]]


However, if I specify that m and n are integers, I only get the 
"general" solution of zero, i.e. when m and n are not equal.

Imn = Simplify[Integrate[
        Sin[(m*Pi*x)/L]*
          Sin[(n*Pi*x)/L],
        {x, 0, L}],
      Element[m, Integers] &&
        Element[n, Integers]]

The workaround is obvious in this case, but shouldn't mma give multiple 
answers? Perhaps something similar to what it already does with Integrate?

Kevin
-- 

Kevin J. McCann
Research Associate Professor
JCET/Physics
Physics Building
University of Maryland, Baltimore County
1000 Hilltop Circle
Baltimore, MD 21250


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